Surface sizing of paper is an operation often followed by paper manufacturers in the case of writing and printing grades of paper. In surface sizing a thin film of a polymer (often a starch derivative) is coated onto the surface of the paper. The film produced on the surface of the paper improves the surface properties of paper, and thereby reduces the catch on the pen when the paper is written on and prevents pick if the paper is printed with tacky inks. Surface sizing also leads to improvement in oil resistance, porosity and smoothness.
The principal sizing agents commonly used in the paper industry are starch, animal glue, carboxymethyl cellulose, methyl cellulose, polyvinyl alcohol, and wax emulsions. Certain synthetic resins are also used for surface sizing of paper. It is felt that the surface properties need to be improved further to provide paper having better printability, smoothness, varnishability, gloss, etc.